Quinoline and naphthyridine antibacterial compounds are well known in the art. For example, Chu U.S. Pat. No. 4,730,000, issued Mar. 8, 1988 describes quinoline compounds with a 7-pyrrolidine substituent group having antibacterial properties, Chu U.S. Pat. No. 4,616,019, issued Oct. 7, 1986 describes naphthyridine compounds with a 7-pyrrolidine substituent group with antibacterial properties, Matsumoto U.S. Pat. No. 4,649,144, issued Mar. 10, 1988 describes 1,8-naphthyridine compounds with a 7-pyrrolidine substituent group with antibacterial activity, and Domagala U.S. Pat. No. 4,735,949, issued Apr. 5, 1988 describes disubstituted 7-pyrrolidinenaphthyridine compounds with antibacterial activity. These compounds, however, have limited aqueous solubility which impairs their use in injectable formulations for intravenous, intramuscular or subcutaneous application. These compounds also have very low solubility at physiological pH which reduces their oral absorption.
In order to improve the solubility of various compounds for pharmaceutical use, their structure has been modified. For example, Gilvarg U.S. Pat. No. 4,479,898, issued Oct. 30, 1984 describes peptide chains substituted by a nucleophilic residue in the alpha position for use as prodrugs to increase cell membrane permeability and Delmotte U.S. Pat. No. 4,753,984, issued June 28, 1988 describes water soluble macromolecular prodrugs in which a polyhydroxylated polyamine is linked to a therapeutically active drug by a peptide chain.